Method and apparatus for preparing massecuite for crystal extraction



I 1966 c. R. STEELE ETAL METHOD AND APPARATUS FOR PREPARING MASSECUITEFOR CRYSTAL EXTRACTION Filed July 5, 1963 INVENTORS.

R. Sfeele Pr! 0 e Clarence Frank B. BY

ATTORNEYS United States Patent f 3,247,021 METHOD AND APIPARATUS FORPREPARENG MASSECUHTE FQR (IRYSTAL EXTRACTEGN tClar-ence R. Stacie andFrank E. Price, Denver, Colo, assignors, by mesne assignments, toAmerican Factors Associates, Limited, Honolulu, fiawaii, a corporationof Delaware Filed July 5, 1963, Ser. No. 292,948 18 Claims. (Cl. 127-15)This invention relates to a method and means for treating massecuiteprior to extraction of its sugar crystal content.

As part of the refining of sugar, mixtures of sugar crystals andassociated liquor are formed, usually comprising sugar crystals inmother liquor, or massecuite. In other operations, sugar magma isproduced which is a mixture of sugar crystals in a foreign liquor. Asused in the specification massecuite will be employed as a genericdefinition and sugar magma will be used as a species definition.

Under optimum conditions, sugar crystals will be formed at aciystallizer stage, or the like, with as much of the sucrose as possibletaken from solution and deposited as crystals. However, none of thecommercial extractions are perfect and there is an economic limit on howfar the extraction can be pursued. The quality of the massecuiteproduced in refining operations is variable and many cane sugartreatments produce what is termed a low-grade massecuite which is veryviscous and difiicult to handle in modern equipment. Incontradistinction, beet sugar refining usually produces massecuitehaving better flowability which permits continuous treatment in therefinery circuit and crystal separation in continuous centrifugalsinstalled in such a circuit.

Accordingly, it is an object of this invention to provide a simple,eflicient and economical method of treating massecuite prior to crystalextraction to increase fiowability and improve sugar yield.

Another object of the invention is to provide a simple, efilcient andeconomical method of feeding viscous massecuite to a continuouscentrifugal for promoting the separation of crystals from solution bythe action of the centrifugal.

A further object of the invention is to provide a simple, economical andefficient crystallization treatment for massecuite for higher sugarcrystal yield and reduced sugar content in solution.

Still another object of this invention is to provide simple, durable andefiicient apparatus for conditioning massecuite to promote crystalformation and increase flowability.

Yet another object of the invention is to provide simple, durable andeificient apparatus which may be automatically controlled to deliverconditioned massecuite to a continuous centrifugal so as to increasesugar extraction by the centrifugal.

The present invention provides several innovations in sugar refiningpractices. It recognizes the need for a conditioning treatment of amassecuite being delivered as feed to a continuous centrifugal. Suchconditioning performs two useful functions. When massecuite is viscous,it tends to ball up on the screen of a continuous centrifugal, does notdistribute uniformly over the screen and thus impairs the efliciency ofthe centrifugal separation. The conditioning step of the presentinvention utilizing a substantial degree of aeration with effectivedistribution of line air bubbles throughout the massecuite by thebeating action of the agitator increases fiowability to a rather uniformdegree and thus delivers feed which the centrifugal can separate atmaximum efiiciency.

Also by such a conditioning treatment, the sucrose or 3,247,921 PatentedApr. 19, 19%6 ice sugar content of the liquor is reduced to asubstantial degree with crystal buildup. As a result, a higher sugaryield is obtained from the massecuite in conjunction with efiicientseparation of crystals from solution by the centrifugal action.

While the apparatus arrangement utilized in the conditioning treatmentis relatively simple, it provides a highly efiicient conditioningtreatment and such treatment may include automatic controls by which apredetermined level is maintained and a desired retention time isprovided in conjunction with treatment in continuous flow. Such controlsalso regulate the rate of feed to the centrifugal which is notoverloaded and operates at optimum efficiency.

The same apparatus may be utilized as a crystallizer stage in sometreatments. In the past, attempts have been made to introduce air intoconventional crystallizer treatments, but such air introduction mayresult in foaming with undesirable consequences. Frequently, the foambecomes so intense as to result in spillage and also impairs theefficiency of the equipment into which the crystallizer discharge is fedat the completion of the crystallization treatment. Further, suchcrystallization treatments have been in the nature of batch treatments,rather than continuous operation, whereas the apparatus of thisinvention may be utilized effectively in a continuous circuit with theefficiency of the crystallization controlled by the amount of gaseousinput and the retention time in the mixing stage.

In this connection, it is possible to use gases other than air in suchtreatments, particularly carbon dioxide and nitrogen. In sugar beetprocessing, CO usually is available in the plant and may be piped tosuch crystallization stage. Aeration as provided by this inventionavoids foam formation, as the beating action of the agitator breaks upany large bubbles tending to form and distributes the air or other gasuniformly throughout the body of massecuite in fine bubble formation. Asa result, the aeration encourages crystal buildup with sucrose takenfrom solution that otherwise would remain in solution.

The practice of this invention will now be described with reference tothe accompanying drawings. In the drawings, in the several views ofwhich like parts bear similar reference numerals,

FIG. 1 is a front elevation of a typical installation utilizing featuresof this invention in the conditioning treatment of massecuite directedin continuous flow as feed to a continuous centrifugal unit;

FIG. 2 is a developed section through the mixing apparatus shown in FIG.1 taken approximately on the line 2-2, and showing the massecuite levelmaintained in the mixer; and

FIG. 3 is a top plan view of the mixing apparatus shown in 1 1G. 1 takenapproximately along the line 3-3.

FIG. 1 illustrates a typical assembly for conditioning massecuite ascontinuous feed to a continuous centrifugal stage. As shown, massecuitefrom a crystallizer stage or other source of supply (not shown) isdelivered by a conduit 10 into the feed end of an elongated troughingmember 11 open at its top and enclosed on its sides and ends forconfining the flow of massecuite in the treatment zone. A shaft 12carrying a series of blades 13 extends horizontally through thetroughing member and is journalled for rotation in an external bearing14 at the discharge end of member 11 and a submerged bearing 15suspended by a rigid hanger 16 at the feed end. An electric motor andspeed reducer 17 drive shaft 12 through suitable transmission 18.

Regulation of feed and discharge is provided to establish a liquid level19 in troughing member 11 which exposes a substantial portion of blades13 in the upper portion of each cycle of rotation and maintains thesurface of the confined body of massecuite in contact with atmosphericair. In a preferred arrangement, alternate blades 13 are pitched atdifferent angles so as to provide a greater degree of mixing of air andmassecuite and to cause portions of the massecuite to be moved fromlower portions of the contained charge to the upper portion thereof forexposure to atmospheric air.

The continued rotation of the shaft 12 and the action of the blades 13carried thereby provides a progressive advance of material through thetroughing member from its point of introduction through conduit 10. Asump outlet 23 is provided at the discharge end of the tank whichdirects the discharge into a conduit 24 at a rate determined by valve 28as the feed to a continuous centrifugal 27. In the arrangement shown,the feed is regulated in relation to discharge with a level sensingdevice or member 25 relating flow through outlet 23 and setting a valve26 in inlet conduit in accordance with such determination so as tomaintain a uniform level 19 in troughing member 11.

From the foregoing, it will be apparent that in a circuiting arrangementsuch as shown in FIG. 1, provision is made to deliver conditionedmassecuite at a desired rate into a continuous centrifugal 27 forseparation of the sugar crystals from associated solution therein. Theconditioning treatment satisfies two objectives, in that the flowabilityof the massecuite is increased so that it is in optimum condition forthe separation action of the centrifugal. In addition, the combinedaeration and agitation as provided in member 11 is effective inobtaining a final sugar extract from the solution which causes a buildupon sugar crystals already formed and results in the discharge of asolution having an extremely low sugar content.

The elongated troughing member 11 of FIG. 1 has been referred to in thepreceding description as being open at its top particularly to supplyatmospheric air in sufiicient quantity to provide the desired aerationin the beating action. If desired, the top of the troughing member maybe covered to protect against deposit of any foreign matter and side orend openings may be provided to maintain sufiicient atmospheric airwithin the enclosure.

Also, when the troughing member is to be utilized in an operation inwhich gas other than atmospheric air is supplied, it will be desirableto have the top fully enclosed and side or end ports (not shown)provided for the introduction of such gas. For example, CO from asuitable plant source may be introduced at low pressure within such anenclosure and the gas supply will be used in sufficient quantity in themixing action to eliminate the need for any exhaust arrangement.However, if desired, a pressure relief valve may be provided to preventbuildup of excess gas pressures.

One of the requirements of eflicient operation with continuouscentrifugal apparatus is that the rate of feed to the centrifugal iscontrolled so as to permit optimum separation by the action of thecentrifugal. As the characteristics of the feed to the centrifugal varyfrom time to time, a constant rate of feed is not satisfactory and inthe practice of the present invention the feed to the centrifugal isdelivered at a variable rate in accordance with a measurement of thepower demand of the centrifugal so that less feed is introduced as thepower demand exceeds an established or predetermined value and increasesas the power demand becomes less than such value.

The circuiting arrangement for the feed control includes a leadconnected to the centrifugal drive motor 29 and passing through atransformer 30 and connected to a transducer assembly 31 in which air isintroduced at 32 and the current representative of the power demand ofthe centrifugal is changed from electrical energy to air pressure andthe air pressure is directed into a pneumatic control 33 in connectionwith an adjusting device 34 regulating the setting of control valve 28.With this arrangement, if the power demand of motor 29 is less than anestablished standard, valve 28 will be opened slightly and if the powerdemand is more than the standard, the valve setting will be changed toreduce the flow into the centrifugal. Valves 35 and a gauge 36 in thetransducer assembly permit operator control in addition to the automaticcontrol of the normal operation of the circuit described above.

We have found that it sometimes is advantageous to the treatment torecirculate a portion of the syrup discharge of the centrifugal into thetroughing member for mixing with the incoming massecuite. Such syrupintro* duction provides a quick thinning effect which is particularlydesirable when a highly viscous massecuite is being treated. A preferredarrangement for providing such action has been illustrated in FIG. 1.Syrup discharge through the syrup outlet 40 of centrifugal 27 isdelivered into a suitable tank or receptacle 41 having means fordividing the flow, with one fraction passing from the centrifugal stagethrough an outlet 42 and another fraction is discharged into the intakeend 43 of a centrifugal pump 44 from which it is conducted through aconduit or line 45 into the feed end of troughing member 11. Preferablyline 45 is valve controlled as shown at 46 so that the total feed tomember 11 can be balanced to the discharge through outlet 23 in themanner previously described.

Even when a highly viscous massecuite is being treated in such acircuit, the discharge through outlet 23 will have a high degree offiowability and by recycling a portion of the syrup or sugar solutiondischarge of centrifugal 27 through the line 45 to the troughing member11, the incoming massecuite delivered into the troughing member throughconduit 10 is promptly mixed with the return material and the mixture isquickly brought to a more flowable condition by the beating action ofblades 13 so that it receives a more intense beating and agitation,coupled with aeration in its progressive movement through the troughingmember.

In the preceding description, different operating prac= tices have beendescribed, some or all of which may be utilized in a given plantoperation. A significant feature of the aeration and beating ofmassecuite or sugar magma is that the feed may be introduced into thetreatment at prevailing temperatures and thus does not require specialpreparation for the treatment practices of this invention.

In preferred practice, the massecuite or sugar magma is treated in aconfined zone in continuous flow with aerating gas maintained orcirculated in contact with the flow along the course of treatment. Suchmaterial with or without extraneous syrup is introduced at the upstreamend of the course and discharged at the downstream end under controlswhich balance input volume to the volume of discharge therebymaintaining a uniform liquid level in the treatment. Consequently, byemploying a troughing member of substantial length and a series ofbeating stages along its length, a substantial quantity of air or otheraerating gas is distributed in the massecuite or magma increasing itsflowability along the course and providing suificient contact betweenthe gas and solution so that the sucrose content in solution issubstantially decreased.

When the massecuite preparation is utilized to control the feed volumeand consistency to a separation stage, such as a continuous centrifugal,such feed can be prepared in optimum condition for such separation.Also, where desired, automatic control may be provided in which thepower demand of the centrifugal is the factor determining the feedcontrol. Also, in such an installation, extraneous solution may becirculated to the mixing and conditioning treatment from the syrupdischarge of such centrifugal.

Finally, in some treatments, the sucrose extraction from the associatedliquor may be utilized to eliminate a crystallizer stage ahead of theconditioning stage of this invention and the fact that the treatment maybe performed at prevailing temperature makes such circuiting practicedesirable in some plants.

We claim:

1. The method of preparing massecuite for crystal extraction, whichcomprises moving massecuite passing from a crystallization stage incontinuous flow through a confined treatment zone of substantial extentsubject to continuous feed and discharge, maintaining aerating gas aboveand in contact with the flow along its course of travel through saidzone, subjecting such flow to a succession of beating actions by aseries of material contacting members spaced longitudinally throughoutthe extent of said confined treatment zone and passing alternately intothe flow of massecuite and into the aerating gas above said flow andthereby inducing entrainment of gas into the massecuite flow as finebubbles, whereby flowability of the massecuite is progressivelyincreased and the sucrose content in solution is deceased, andcontinuously discharging the aerated flow after a predeterminedtreatment interval in said zone as feed directly into a continuouscentrifugal separation stage.

65,. The method of preparing massecuite for crystal ex traction, whichcomprises moving massecuite passing from a crystallization stage incontinuous flow through a confined treatment zone of substantial extentsubject to continuous feed and discharge, maintaining aerating gas aboveand in contact with the flow along its course of travel through saidzone, subjecting such flow to a succession of beating actions by aseries of material contacting members spaced longitudinally throughoutthe extent of said confined treatment zone and passing alternately intothe flow of massecuite and into the aerating gas above said flow andthereby inducing entrainment of gas into the massecuite flow as finebubbles, whereby flowability of the massecuite is progressivelyincreased and the sucrose content in solution is decreased, maintaininga uniform massecuite level in said zone by balancing the volume of inputto the volume of discharge from said zone, and continuously dischargingthe aerated flow after a predetermined treatment intenval in said zoneas feed directly into a continuous centrifugal separation stage in saidzone.

3. The method of preparing massecuite for crystal extraction, whichcomprises moving massecuite passing from a crystallization stage incontinuous fiow through a confined treatment zone of substantial extentsubject to continuous feed and discharge, maintaining circulating airabove and in contact with the flow along its course of travel throughsaid zone, subjecting such flow to a succession of beating actions by aseries of material contacting members spaced longitudinally throughoutthe extent of said confined treatment zone and passing alternately intothe flow of massecuite and into the air above said flow and therebyinducing entrainment of air into the massecuite flow as fine bubbles,whereby flowability of the massecuite is progressively increased and thesucrose content in solution is decreased, and continuously dischargingthe aerated flow after a predetermined treatment interval in said zone.

4. The method of preparing massecuite for crystal extraction, whichcomprising moving massecuite passing from a crystallization stage incontinuous ilow through a confined treatment zone of substantial extentsubject to continuous feed and discharge, maintaining circulating COabove and in contact With the flow along its course of travel throughsaid zone, subjecting such flow to a succession of beating actions by aseries of material contacting members spaced longitudinally throughoutthe extent of said confined treatment zone and passing alternately intothe flow of massecuite and into the CO above said flow and therebyinducing entrainment of CO into the massecuite flow as fine bubbles,whereby flowability of the massecuite is progressively increased and thesucrose content in solution is decreased, and continuously dischargingthe aerated'flowafter a predetermined treatment interval in said zone asfeed directly into a continuous centrifugal separation stage.

5. The method of preparing massecuite for crystal extraction, whichcomprises moving massecuite passing from a crystallization stage incontinuous flow through a confined treatment zone of substantial extentsubject to continuous feed and discharge, maintaining aerating gas aboveand in contact with the How along its course of travel through saidzone, subjecting such flow to a succession of beating actions by aseries of material contacting members spaced longitudinally throughoutthe extent of said confined treatment zone and passing alternately intothe flow of massecuite and into the aerating gas above said flow andthereby inducing entrainment of gas into the massecuite flow as finebubbles, whereby flowability of the massecuite is progressivelyincreased and the sucrose content in solution is decreased, anddischarging the aerated massecuite after a predetermined retentioninterval as the feed to a continuous centrifugal separation stage.

6-. The method of preparing massecuite for crystal extraction, whichcomprises moving massecuite passing from a crystallization stage incontinuous flow through a confined treatment zone of substantial extentsubject to continuous feed and discharge, maintaining aerating gas aboveand in contact with the flow along its course of travel through saidzone, subjecting such flow to a succession of beating actions by aseries of material contacting members spaced longitudinally throughoutthe extent of said confined treatment zone and passing alternately intothe fiow of massecuite and into the aerating gas above said flow andthereby inducing entrainment of gas into the massecuite flow as finebubbles, whereby flowability of the massecuite is progressivelyincreased and the sucrose content in solution is decreased, anddischarging the aerated massecuite after a predetermined treatmentinterval as feed at a controlled rate to a continuous centrifugalseparation stage.

7. The method of preparing massecuite for crystal extraction, whichcomprises moving massecuite passing from a crystallization stage atprevailing temperatures in con tinuous flow through a confined treatmentzone of substantial extent subject to continuous feed and discharge,maintaining aerating gas above and in contact with the flow along itscourse of travel through said zone, subjecting such flow to a successionof beating actions by a series of material contacting members spacedlongitudinally throughout the extent of said confined treatment zone andpassing alternately into the flow of massecuite and into the aeratinggas above said flow and thereby inducing entrainment of gas into themassecuite flow as fine bubbles, whereby flowability of the massecuiteis prorgessively increased and the sucrose content in solution isdecreased, and continuously discharging the aerated flow after apredetermined treatment interval in said zone as feed directly into acontinuous centrifugal separation stage.

8. The method of preparing massecuite for crystal extraction, whichcomprises moving massecuite passing from a crystallization stage incontinuous flow through a confined treatment zone of substantial extentsubject to continuous feed and discharge, maintaining aerating gas aboveand in contact with the flow along its course of travel through saidzone, subjecting such flow to a succession of beating actions by aseries of material contacting members spaced longitudinally throughoutthe extent of said confined treatment zone and passing alternately intothe flow of massecuite and into the aerating gas above said flow andthereby inducing entrainment of gas into the massecuite flow as finebubbles, whereby flowability of the massecuite is progressivelyincreased and the sucrose content in solution is decreased, maintaininga uniform massecuite level in said zone by balancing the volume of inputto the volume of discharge from said zone, continuously discharging theaerated flow directly into a centrifugal separation stage, and recyclingsome of the separated syrup of the separation stage into the massecuiteflow adjacent its upstream end.

9. The method of preparing massecuite for crystal extraction, whichcomprises moving massecuite and extraneous syrup passing from acrystallization stage in continuous flow through a confined treatmentzone of substantial extent subject to continuous feed and discharge,maintaining aerating gas above and in contact with the flow along itscourse of travel through said zone, subjecting such flow to a successionof beating actions by a series of material contacting members spacedlongitudinally throughout the extent of said confined treatment zone andpassing alternately into the flow of massecuite and into the aeratinggas above said flow and thereby inducing entrainment of gas into themassecuite flow as fine bubbles, whereby fiowability of the massecuiteis progressively increased and the sucrose content in solution isdecreased, and continuously discharging the aerated flow after apredetermined treatment interval in said zone as feed directly into acontinuous centrifugal separation stage.

10. The method of preparing massecuite for crystal extraction, whichcomprises moving massecuite and extraneous syrup passing from acrystallization stage in continuous flow through a confined treatmentzone of substantial extent subject to continuous feed and discharge,maintaining aerating gas above and in contact with the flow along itscourse of travel through said zone, subjecting such flow to a successionof beating actions by a series of material contacting members spacedlongitudinally throughout the extent of said confined treatment zone andpassing alte-rnately into the flow of massecuite and into the aeratinggas above said how and thereby inducing entrainment of gas into themassecuite flow as fine bubbles, whereby flowability of the massecuiteis progressively increased and the sucrose content in solution isdecreased, continuously discharging the aerated fiow directly into acentrifugal separation stage, recycling some of the separated syrup ofthe separation stage at a controlled rate into the massecuite flowadjacent its upstream end, and maintaining a uniform massecuite level inthe treatment zone by balancing the volume of input material to thevolume of discharge from said zone.

11. The method of preparing massecuite for crystal extraction, whichcomprises moving massecuite passing from a crystallization stage incontinuous flow through a confined treatment zone of substantial extentsubject to continuous feed and discharge, maintaining circulatingnitrogen above and in contact with the fiow along its course of travelthrough said zone, subjecting such flow to a succession of beatingactions by a series of material contacting members spaced longitudinallythroughout the extent of said confined treatment zone and passingalternately into the flow of massecuite and into the nitrogen above saidflow and thereby inducing entrainment of nitrogen into the massecuiteflow as fine bubbles, whereby flowability of the massecuite isprogressively increased and the sucrose content in solution isdecreased, and continuously discharging the aerated flow after apredetermined treatment interval in said zone as feed directly into acontinuous centrifugal separation stage.

12. The method of extracting the sucrose content from mother liquor inthe treatment of massecuite in a continuous flow through a confined zoneof substantial extent which comprises directing the continuous flow ofmassecuite passing from a crystallization stage along an enclosed coursesubject to continuous feed and discharge and in contact with a confinedbody of aerating gas, inducing entrainment of the aerating gas into themassecuite flow in fine bubble formation by beating the massecuite in asuccession of stages by a series of material contacting members spacedlongitudinally throughout the extent of said confined treatment zone andpassing alternately into the flow of massecuite and into the aeratinggas above said flow and thereby, whereby crystal formation in themassecuite is increased by sucrose extraction from associated solution,and continuously discharging aerated massecuite'after a predeterminedmixing in said flow as feed directly into a continuous centrifugalseparation stage.

13. The method of extracting the sucrose content from liquor in thetreatment of sugar magma in a continuous flow through a confined zone ofsubstantial extent which comprises directing the continuous fiow ofmagma along. an enclosed course subject to continuous feed and dis--charge and in contact with a confined body of aerating gas,.

inducing entrainment of the aerating gas into the magma flow in finebubble formation by beating the magma in a succession of stages by aseries of material contacting members spaced longitudinally throughoutthe extent of said confined treatment zone and passing alternately intothe flow of magma and into the aerating gas above said fiow and thereby,whereby crystal formation in the magma is increased by sucroseextraction from associated solution, and continuously dischargingaerated magma after a predetermined mixing in said flow as feed directlyinto continuous centrifugal separation stage.

14. Apparatus for preparing massecuite for crystal extraction,comprising an elongated troughing member open at its top and enclosed onits sides and ends for confining a horizontal flow of massecuite and abody of aerating gas above said flow, a valve-controlled outlet at thedownstream end of the troughing member for regulating the rate ofoutflow of treated massecuite from said member, means for passing thetreated massecuite from said outlet as feed directly into a continuouscentrifugal separation stage, means for feeding massecuite passing froma crystallization stage into said member at its upstream end at acontrolled rate related to the discharge rate and determining a liquidlevel therein, a rotary shaft extending lengthwise through the interiorof the troughing member and carrying a plurality of blades at intervalsthroughout its length rotating in close proximity to the bottom of themember and above the liquid level in each cycle of rotation for beatingthe flowing massecuite and entraining air in fine bubble formationtherein so as to increase flowability of the massecuite, and drive meansfor rotating said shaft.

15. Apparatus for preparing massecuite for crystal extraction,comprising an elongated troughing member open at its top and enclosed onits sides and ends for confining a horizontal How of massecuite and abody of aerating gas above said flow, a valve-controlled outlet at thedownstream end of the troughing member for regulating the rate ofoutflow of treated massecuite from said member, means for passing thetreated massecuite from said outlet as feed directly into a continuouscentrifugal separation stage, sensing means for relating the rate offlow through said outlet to the liquid level in the troughing member,means for feeding massecuite passing from a crystallization stage intosaid member at its upstream end at a controlled rate established by thesensing means and determining a liquid level therein, a rotary shaftextending lengthwise through the interior of the troughing member andcarrying a plurality of blades at intervals throughout its lengthrotating in close proximity to the bottom of the member and above theliquid level in each cycle of rotation for beating the flowingmassecuite and entraining air in fine bubble formation therein so as toincrease flowability of the massecuite, and drive means for rotatingsaid shaft.

16. Apparatus for preparing massecuite for crystal extraction,comprising an elongated troughing member open at its top and enclosed onits sides and ends for confining a horizontal flow of massecuite and abody of aerating gas above said flow, a valve-controlled outlet at thedownstream end of the troughing member for regulating the rate ofoutflow of treated massecuite from said member, means for passing thetreated massecuite from said outlet as feed directly into a continuouscentrifugal separation stage, sensing means for relating the rate offlow through said outlet to the liquid level in the troughing member,means for feeding massecuite passing from a crystallization stage intosaid member at its upstream end at a controlled rate established by thesensing means and determining a liquid level the-rein, a rotary shaftextending lengthwise through the interior of the troughing member andcarrying a plurality of blades at intervals throughout its lengthrotating in close proximity to the bottom of the member and above theliquid level in each cycle of rotation for beating the massecuite andentraining air in fine bubble formation therein so as to increaseflowability of the massecuite, and drive means for rotating said shaft.

17. Apparatus for preparing massecuite for crystal extraction,comprising an elongated troughing member open at its top and enclosed onits sides and ends for confining a horizontal flow of massecuite and abody of aerating gas above said flow, a valve-controlled outlet at thedownstream end of the troughing member for regulating the rate ofoutflow of treated massecuite from said member, means for passing thetreated massecuite from said outlet as feed directly into a continuouscentrifugal separation stage means for feeding massecuite passing from acrystallization stage into said member at its upstream end at acontrolled rate related to the discharge rate and determining a liquidlevel therein, a rotary shaft extending lengthwise through the interiorof the troughing member and carrying a plurality of blades at intervalsthroughout its length rotating in close proximity to the bottom of themember and above the liquid level in each cycle of rotation for beatingthe flowing massecuite and entraining air in fine bubble formationtherein so as to increase flowability of the massecuite, the blades atalternate intervals being pitched differently than the bladesintermediate said intervals, and drive means for rotating said shaft.

18. The method of preparing massecuite for crystal extraction, whichcomprises moving massecuite passing from a crystallization stage incontinuous flow through a confined treatment zone of substantial extentsubject to continuous feed and discharge, maintaining aerating gas aboveand in contact with the flow along its course of travel through saidzone, subjecting such flow to a succession of beating actions by aseries of material contacting members spaced longitudinally throughoutthe extent of said confined treatment zone and passing alternately intothe flow of massecuite and into the aerating gas above said flow andthereby inducing entrainment of gas into the massecuite flow as finebubbles, whereby fiowability of the massecuite is progressivelyincreased and the sucrose content in solution is decreased, maintaininga uniform massecuite level in said zone by balancing the volume of inputto the volume of discharge from said zone, continuously discharging theaerated flow into a continuous centrifugal separation stage, andregulating the discharge into the centrifugal separation stage inaccordance with a measurement of the power demand of said centrifugalseparation stage.

References Cited by the Examiner UNITED STATES PATENTS 242,216 5/1831Morrell 127-2 X 675,938 6/1901 Delafond 12 7-58 988,261 3/1911 Griere127-58 1,334,395 3/1920 Patterson 127-22 1,862,719 6/1932 Spreckels12760 2,032,160 2/ 193-6 Widmer 127-58 2,206,237 7/ 1940 Roberts 127-64X 2,347,288 4/ 1944 Schle-gel et al 127--l 5 FOREIGN PATENTS 310,369 3/1929 Great Britain. 570,101 6/ 1922 Great Britain.

OTHER REFERENCES Honig, Principles of Sugar Technology, vol. III,Crystallization, Elseview Publishing Co., New York, 1959, pp. 3-454.

Spencer-Meade, Cane Sugar Handbook, eighth edition, 1945, John Wiley andSons, New York, pp. 207-216 and 2262 29.

MORRIS O. WOLK, Primary Examiner.

14. APPARATUS FOR PREPARING MASSECUITE FOR CRYSTAL EXTRACTION,COMPRISING AN ELONGATED TROUGHING MEMBER OPEN AT ITS TOP AND ENCLOSED ONITS SIDES AND ENDS FOR CONFINING A HORIZONTAL FLOW OF MASSECUITE AND ABODY OF AERATING GAS ABOVE SAID FLOW, A VALVE-CONTROLLED OUTLET AT THEDOWNSTREAM END OF THE TROUGHING MEMBER FOR REGULATING THE RATE OFOUTFLOW OF TREATED MASSECUITE FROM SAID MEMBER, MEANS FOR PASSING THETREATED MASSECUITE FROM SAID OUTLET AS FEED DIRECTLY INTO A CONTINUOUSCENTRIFUGAL SEPARATION STAGE, MEANS FOR FEEDING MASSECUITE PASSING FROMA CRYSTALLIZATION STAGE INTO SAID MEMBER AT ITS UPSTREAM END AT ACONTROLLED RATE RELATED TO THE DISCHARGE RATE AND DETERMINING A LIQUIDLEVEL THEREIN, A ROTARY SHAFT EXTENDING LENGTHWISE THROUGH THE INTERIOROF THE TROUGHING MEMBER AND CARRYING A PLURALITY OF BLADES AT INTERVALSTHROUGHOUT ITS LENGTH ROTATING IN CLOSE PROXIMITY TO THE BOTTOM OF THEMEMBER AND ABOVE THE LIQUID LEVEL IN EACH CYCLE OF ROTATION FOR BEATINGTHE FLOWING MASSECUITE AND ENTRAINING AIR IN FINE BUBBLE FORMATIONTHEREIN SO AS TO INCREASE FLOWABILITY OF THE MASSECUITE, AND DRIVE MEANSFOR ROTATING SAID SHAFT.